Heat properly in winter
Contrary to popular opinion, it is better to set a conventional thermostat gas heating to level 2 (if it is really nasty cold 3) and always start, even if you are one-day away and at night.
Then the walls and furniture get the temperature, and the heat stays stored longer. The heating is then usually still rather cool. Otherwise the heating would have to heat up completely to level 4 or 5 again and again.
When venting, you can then make it short, but then you should also open the windows properly and only a few minutes to air (you do not want to heat outside). This is best done in the whole apartment.
